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04-Dec-2021   
Path: RAMI-IV : EXPERIMENTS : ACTUAL CANOPIES : OFENPASS WINTER PINESTAND
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Ofenpass Pine Stand (Winter): HET08_OPS_WIN

This page provides descriptions of the architectural, spectral and illumination related properties of a mountain pine (Pinus montana) stand located in the eastern Ofenpass valley of Switzerland. The forest stand features trees aged between 90 and 200 years and has been without management since 1914. The Ofenpass pine stand description provided below is based on inventory data gathered by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), as well as, field and Lidar data acquired and processed by Felix Morsdorf, Ben Kötz and colleagues from the Remote Sensing Laboratories (RSL) of the University of Zurich, Switzerland. Potential RAMI participants are to treat the information presented on this page as actual 'inventory data', that is, they should identify/extract those parameters and characteristics that are required as input to their canopy reflectance models. In some cases this may mean that simplifications have to be made to the available information, or, that parts of the available information cannot be - or have to be modified before being - exploited with a given radiative transfer model. Whatever the case may be, all potential RAMI participants should mimic the standard practices that they use when matching actual field measurements to the required set(s) of input parameters for their model(s). If this means that you need more information than provided, please do not hesitate in contacting us. Last but not least, for those 3D models capable of maintaining architectural fidelity down to the individual shoot and branch level a series of ASCII (text) files containing the Cartesian coordinates of various geometric primitives (triangles, spheres and cylinders) and their transformations will be given.

In order to facilitate the generation of the Ofenpass Mountain Pine stand (winter) the information on this page has been subdivided into four different categories. For each one of these categories the relevant descriptions will be contained within a uniquely coloured text frame and can be accessed by clicking on one of the four links below:

architectural
characteristics
spectral
characteristics
illumination
characteristics
measurements
characteristics

In case of difficulties or missing data on this page please do not hesitate in contacting us so that the problems may be resolved as fast as possible.


Architectural information up

1) General canopy characteristics

The Ofenpass Mountain Pine forest inventory was carried out over a large area from which a 100×100 m² subplot was selected for RAMI. The origin of the coordinate system was placed at the south-western end of this area. However, in order to include the tree crowns of those trees that were located within the 1 hectare area of the RAMI Mountain Pine Winter stand representation it was necessary to expand the scene area slightly beyond the one hectare. Maintaining the origin of the tree location coordinate system thus resulted in some negative x,y values in the table below. Overall architectural characteristics of the scene are thus as follows:

Scene dimensions:(X × Y × Z) 103.1214 × 103.2308 × 15.0213 [m × m × m]
(Xmin, Ymin, Zmin) −1.6521, −1.9206, 0.0 [m, m, m]
(Xmax, Ymax, Zmax) 101.4693, 101.3102, 15.0213 [m, m, m]
Number of trees in scene 991 (621 live, 120 dead, 250 understorey)
Leaf Area Index of scene* 0.744870
Fractional scene coverage** 0.1248
*The LAI of the pine trees is computed using half the total area of the needles in a shoot.
**The fractional cover is defined as 1 - direct transmission at zero solar zenith angle.

2) Foliage structure

The table below provides the architectural characteristics of the shoots of the trees used in the Ofenpass Pine stand representation. Individual shoots are generated by stacking four sub-shoots - with architectures based on the geometry proposed by Smolander et al., 2003 (RSE) - on top of each other. RT models capable of representing the architecture of individual foliage elements with a series of geometric primitives (triangle, sphere, cylinder) may want to use the information provided in the ASCII (text) files accessible from the last row in each table below.

Mountain pine shoot
number of needles 240
total needle area* 224.614 cm²
needle lengtho 2.8 and 4.5 cm
needle diameter 0.05 cm
angle between twig and needleo 30° and 40°
fascicle angle 0 - 27.7°
twig length 9.0 cm
twig diameter 0.5 cm
structural description file (geometric primitives) click here
* This total needle area value arises if the needles are represented as elongated spheres (as is the case in the ASCII file accessible via the link in the last row of the above table). If individual needles are represented as cylinders (with discs as endcaps) then the total needle area of the shoot is different and the number of shoots per mountain pine tree should be adjusted accordingly.
o For a detailed description of the shoot structure please read the header of the structural description file accessible via the link in the last row of this table.

3) Tree structure

The Ofenpass Mountain Pine forest is generated on the basis of 13 individual tree representations. Twelve of these pertain to live Mountain pine (Pinus Montana) trees and one refers to a dead Mountain pine tree representation. The latter is due to the fact that about 20% of the overall tree density is made up of dead (standing) trees. The table below provides an overview of some structural characteristics of these various tree representations. For those RT models capable of representing the 3D architecture of a given trees in a voxelised manner, or alternatively, through a series of geometric primitives the last four lines of this table contain links to data files with detailed specifications of the foliage and wood structural properties of the Ofenpass Mountain Pine forest (Winter) trees.

TABLE 1:
tree identifierPIMO1PIMO2PIMO3PIMO4PIMO5PIMO6PIMO7
tree height [m]3.245.996.518.849.0811.0110.61
diameter at breast height (DBH) [cm]8.011.012.415.413.416.824.4
Foliage normal distribution: zenith angle=graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
Foliage normal distribution: azimuth angle=graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
height to live/green crown [m]0.321.432.063.224.774.967.38
crown radiusx
mean [m]:
maximum [m]:
picture
0.27
0.94
picture
0.23
1.02
picture
0.46
1.34
picture
0.42
1.15
picture
0.25
1.03
picture
0.57
1.70
picture
0.38
1.18
vertical profile of crown radii* [m]graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
half-total foliage area of tree# [m²]17.08194.0879823.191417.63224.570914.39785.42443
vertical profile of leaf area o [m²]graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
total wood area of tree [m²]2.11752.534445.969515.841874.83909.9318611.5582
vertical profile of wood areao [m²]graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
tree shape image
foliage structure (triangle mesh)filefilefilefilefilefilefile
wood structure (triangle mesh)filefilefilefilefilefilefile

TABLE 2:
tree identifierPIMO8PIMO9PIMO10PIMO11PIMO12PIMO13PIMO14
tree height [m]13.6013.0712.3914.6515.1210.021.09
diameter at breast height (DBH) [cm]32.434.634.436.025.622.6NA
Foliage normal distribution: zenith angle=graph
data
graph
data
graph
data
graph
data
graph
data
NAgraph
data
Foliage normal distribution: azimuth angle=graph
data
graph
data
graph
data
graph
data
graph
data
NAgraph
data
height to live/green crown [m]2.827.6710.238.8110.32NA0.12
crown radiusx
mean [m]:
maximum [m]:
picture
0.60
1.77
picture
0.33
1.18
picture
0.27
1.08
picture
0.54
1.70
picture
0.36
1.20
picture
0.14
0.77
picture
0.17
0.43
vertical profile of crown radii* [m]graph
data
graph
data
graph
data
graph
data
graph
data
NAgraph
data
half-total foliage area of tree# [m²]20.12546.74972.2124515.70054.35750.05.89612
vertical profile of leaf area o [m²]graph
data
graph
data
graph
data
graph
data
graph
data
NAgraph
data
total wood area of tree [m²]20.070212.687211.322719.739512.93585.541470.32731
vertical profile of wood areao [m²]graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
graph
data
tree shape image
foliage structure (triangle mesh)filefilefilefilefileNAfile
wood structure (triangle mesh)filefilefilefilefilefilefile
= The zenith angle of the foliage normal is defined as the angle between the vertical and the normal of the main twig of the shoot (for a shoot axis aligned along the z-axis the normal was arbitrarily chosen to lie along the y-axis). Rather than spanning the full range of possible zenith angles (i.e., from 0 to 180 degree) as could be expected for non-flat asymmetric objects, it was chosen to follow the convention of foliage normals pointing only into the upper hemisphere. This is because RAMI participants, that make use of this foliage normal distribution information, will in all likelihood have models where scatterers are represented as flat (disc or equilateral triangle shaped) objects. However, should your model require a description of the foliage normal zenith angle distribution up to 180 degrees then please do not hesitate in contacting us and we will provide this information to you. For both the zenith and azimuth angle distributions the 'graph' link shows an image of the normalised foliage normal distribution versus zenith (or azimuth) angle of the foliage normal. The 'data' files for the zenith and azimuth angle distribution have three columns indicating 1) the upper value of the zenith (or azimuth) angle in a given bin, 2) the fraction of foliage area having a normal in this zenith (or azimuth) angle range, and 3) the fraction of wood area having a normal that falls in this zenith (or azimuth) angle range. Bin angle widths were chosen to be 5 degrees and 10 degrees for zenith and azimuth angles, respectively.
x The crown radius of actual trees is varying with azimuth angle. This can be seen in the various pictures showing a perspective-free nadir view of a given tree located at x=0,y=0 (concentric circles indicate the distance from the origin in steps of 0.25m). The mean and maximum values were computed from the triangle objects making up the 3D trees depicted in the picture in the the fourth-last row of each table column.
* The graphs show the maximum radial distance of foliage elements in a given height interval plotted against the upper height level of that height interval. The data files have five columns: lower-height-of-bin-in-units-of-meters     upper-height-of-bin-in-units-of-meters     minimum_radial-distance_of_foliage-in-units-of-m     maximum_radial-distance_of_foliage-in-units-of-m.     mean_radial-distance_of_foliage-in-units-of-m
# This value corresponds to the one-sided leaf area for flat leaves. For Mountain pine trees it corresponds to the sum of the (maximum) silhouettes of all the individual needles in the tree (i.e., half the total needle area per tree).
o The data files have 3 columns: lower-height-of-bin-in-units-of-meters     upper-height-of-bin-in-units-of-meters     area-of-wood-or-foliage-in-units-of-m2.

4) Stand structure

The Ofenpass Mountain Pine forest is composed of 991 individual trees. The following table indicates how these trees are distributed among the above tree classes and specifies their respective x,y locations of the tree centers of each tree class in the forest stand. The last row of this table contains an ASCII file with tree rotation and translation information for those RT models capable of ingesting the detailed 3D architecture of the tree models specified in the previous section.

tree identifierPIMO1PIMO2PIMO3PIMO4PIMO5PIMO6PIMO7PIMO8PIMO9PIMO10PIMO11PIMO12PIMO13PIMO14
tree number per class 15364332505910329131602538120250
x,y coordinates of tree centers [m,m] datadatadatadatadatadatadatadatadatadatadatadatadatadata
tree rotations and translation (ASCII file)x datadatadatadatadatadatadatadatadatadatadatadatadatadata
x These files contain pseudo code to rotate individual trees around their z axis and translate them from the origin to the x,y locations specified in the data files of the previous row of this table. Positive rotation angles in these files indicate that when looking down from the positive Z axis towards the origin of the coordinate system a counterclockwise rotation will result in moving the positive x axis towards the positive y axis. The angle of rotation is in the 7th column of these data files (starting the count from 1).

The Figure below shows the tree locations for the Ofenpass Mountain pine (Winter) stand. Crown of live trees are open circles. Red dots are trees belonging to the (randomly dispersed) understorey. Black dots are (randomly dispersed) dead trees. The origin of the coordinate system is in the lower left hand side corner of the image.


RAMI participants with 3D RT models capable of representing objects using geometric primitives can download a single compressed ZIP archive with all the tree architectural ASCII information that is listed in the above tables by clicking HERE. Note: The size of the compressed archive is about 1.8 megabytes. It contains 42 ASCII files and can be unzipped using 'WINZIP' on windows or 'unzip' on linux/unix operating systems. Beware that the inflated archive will take up 9.7 Megabytes of storage.

spectral canopy characteristics up

Only the foliage and woody components in the Ofenpass pine stand (Winter) scene feature LAMBERTIAN scattering properties. The background properties on the other hand are NON-LAMBERTIAN. To capture the directional variability of the hemispherical directional reflectance factor (HDRF) of snow, the RPV model has been fitted to a series of actual goniometer observations. The tables below contains the magnitudes of the reflectance and transmission characteristics of the various canopy components for nineteen different spectral bands as well as the RPV parameters describing the anisotropy of the background HDRF. The experimental identifier for the Ofenpass Pine Stand (Winter) scene is given by HET08_OPS_WIN_B**_47 where B** relates to the spectral bands (B01, B02, …, B19). An ASCII (text) file that resumes all of this information can be found here.

Mountain Pine: Lambertian scatterer

band IDB01B02B03B04B05B06B07B08B09B10
needle reflectance0.043160.051440.100540.116400.106210.076960.061130.057330.117100.18140
needle transmittance0.011860.016460.046380.055950.047780.028920.021000.019040.055190.10751
stem reflectanceo0.070310.073430.075740.077200.078560.083530.086470.087820.090850.09228
 
band IDB11B12B13B14B15B16B17B18B19
needle reflectance0.227540.382480.398720.407270.416380.416560.415750.404490.5
needle transmittance0.150710.299450.299450.326210.337190.338240.338240.333660.5
stem reflectanceo0.093300.098160.099610.103800.119370.124520.128020.156731.0
o The transmittance for woody elements (stem and branches) is equal to zero.

Background: Anisotropic scatterer

band IDB01B02B03B04B05B06B07B08B09B10
RPV ρ00.8741540.8527920.8496580.8483040.8478620.8451800.8370760.8361750.8307650.827047
RPV k1.0090201.0029301.0038001.0044501.0049801.0070001.0056701.0054101.0048001.003840
RPV Θ0.0561820.0562460.0587700.0603190.0612630.0639160.0640640.0640170.0648870.064917
RPV ρc0.8004550.7490300.7338450.7254980.7217170.7212580.7096990.7106240.7071160.702685
RPV data#filefilefilefilefilefilefilefilefilefile
 
band IDB11B12B13B14B15B16B17B18B19
RPV ρ00.8237840.8153200.8148550.7953300.7737740.7562810.7614870.6568671.0
RPV k1.0032201.0023001.0034100.9998770.9996220.9959971.0006700.9820861.0
RPV Θ0.0652370.0666150.0673500.0706380.0723730.0729840.0767450.0891450.0
RPV ρc0.6966060.6861880.6978750.6763580.7034110.7133580.7306270.6671591.0
RPV data#filefilefilefilefilefilefilefilefile
# These files are the BRF output generated by the RPV code when fed with the above input parameters. Note that the solar zenith angle in these files takes account of the direction of the incident light. It thus lies in the range [90-180] and is computed as 180 - SZA, where SZA is the solar zenith angle defined below. A relative azimuth of 0 (180) degree relates to forward (backward) scattering conditions. For more information on RPV please look here. Participants who wish to fit their own anisotropic background model to the RPV-simulated BRF data should inform the RAMI coordinators of this via the report files.

illumination characteristics up

The illumination conditions for the Ofenpass Mountain Pine forest stand feature both direct and isotropic diffuse components. Direct solar light is characterised by a solar zenith angle (SZA) of 47.0 degree and a solar azimuth angle equal to 151.3 degree. The table below indicates the ratio of isotropic diffuse to total incident radiation for the nineteen different spectral bands:

spectral identifierB01B02B03B04B05B06B07B08B09B10
diffuse/total solar flux ratiox0.26600.18920.15680.14210.12910.09310.08280.07950.07670.0756
 
spectral identifierB11B12B13B14B15B16B17B18B19
diffuse/total solar flux ratiox0.07480.07130.07000.06650.05550.05380.05270.04460.0
x The 'direct/total solar flux ratio' is thus equal to 1 - (diffuse/total solar flux ratio).

The figure below shows a perspective-free view of the Ofenpass Mountain pine stand with the Cartesian coordinate system and the direction of the incident solar radiation (blue arrow) superimposed. Azimuth angles are counted in an anti-clockwise direction from the positive X-axis towards the positive Y-axis as indicated by the (dotted blue) arc around the origin.


measurement characteristics up

The experimental identifier <EXP> that is needed in the naming of the various measurement results files (see file naming and formatting conventions) for the Ofenpass Pine Stand (Winter) scene is given by HET08_OPS_WIN_B**_47 where B** relates to the spectral bands (B01, B02, …, B19). For each one of these spectral bands a series of radiative measurements have to be performed. In addition a lidar experiment and a fisheye experiment are proposed.

The following are the prescribed measurements for the Ofenpass Mountain Pine stand (Winter):


Prior to the performing of any RT model simulations, please refer to the 'definitions' pages for detailed instructions regarding the angular sign conventions for BRF simulations, as well as other RT model technicalities. Also read the relevant file naming and formatting conventions that must be adhered to by all participants. In addition, RAMI-IV offers participants the possibility to test the compliance of their model-generated results files with these file-naming and formatting convention, prior to their submission via ftp: To do so follow the on-line format checker link that appears in the top navigation bar during the active submission period.

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